The relatively low operating voltage window of aqueous energy storage devices is a key parameter that limits their energy density. Electrode materials with high electrochemical activities and a wide stable working potential range are crucially needed. Herein, we reported a strategy to control the working potential range of the negative electrode by optimizing the component proportion of molybdenum-tungsten-oxide solid-state solutions. The operating potential range of the molybdenum-tungsten-oxide solid-state solutions was tunable between −0.4 and −1.2 V. An asymmetric supercapacitor device was fabricated by using a Mo0.1W0.9O3-x/single-walled carbon nanotube film as the negative electrode and a commercial activated carbon film as the positive electrode. The optimized device showed a stable working voltage of 2.0 V in 1 M Li2SO4 aqueous electrolyte. This study opens up new avenues for developing high voltage window aqueous energy storage devices.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: We gratefully acknowledge the financial support by Science and Technology Commission of Shanghai Municipally (16JC1400700), Innovation Program of Shanghai Municipal Education Commission (2017-01-07-00-03-E00055), the Shanghai Natural Science Foundation (16ZR1401500), the Shanghai Sailing Program (16YF1400400), and the Program of Introducing Talents of Discipline to Universities (No.111-2-04). J. L. acknowledges support through the Fundamental Research Funds for the Central Universities (CUSF-DH-D-2017028). We thank Jim Bailey, PhD, from Liwen Bianji, Edanz Editing China (www.liwenbianji.cn/ac), for editing the English text of a draft of this manuscript.